Foundry induction furnaces are well known in the art. A typical foundry furnace includes a refractory base and a cylindrical outer wall extending vertically about the periphery of the base. An induction heating coil is accommodated by the outer wall. A continuous lining formed of sintered silica or other refractory material lines the cylindrical wall to define a chamber for molten metal such as iron melt.
From time to time, the lining of refractory material becomes eroded and requires replacement. When the foundry furnace is to be relined, an expendable steel form is concentrically disposed within the foundry furnace. Particulate refractory material is then poured into the annular space between the form and the cylindrical outer wall. The refractory material is sintered first by gas heaters fired into the foundry furnace and thereafter, by an initial charge of molten metal poured into the form. The molten metal melts the form to reveal the sintered lining.
During the relining process, it is important to ensure that the lining is uniform in thickness about the cylindrical outer wall since variations in lining thickness physically weaken the lining and create pockets where molten metal in the foundry furnace may be overheated. Therefore, when the form is being placed in the foundry furnace, it is important that the form be centrally positioned so that the annular space between the form and the outer cylindrical wall is uniform about its circumference.
Currently when a foundry furnace is to be relined, the form is suspended by a hoist and lowered into the foundry furnace. Workers positioned at circumferentially spaced locations about the foundry furnace hold onto the form as it is being lowered and guide the form in an attempt to place the form concentrically within the foundry furnace. Once the form has been lowered, the workers visually inspect the annular space between the form and the cylindrical outer wall to determine if the annular space is uniform. If the annular space does not appear to be uniform, the form is lifted and the process is repeated. In most instances, many attempts must be made before the form appears to be concentrically positioned within the foundry furnace. This of course lengthens the relining procedure and therefore, increases the downtime of the foundry furnace. Accordingly, improvements to foundry furnace relining procedures are desired.
It is therefore an object of the present invention to provide a novel method of installing a form in a foundry furnace.